The invention relates to an electrically conductive connection of the active parts of an electrical component, particularly of a surface wave filter, or of an integrated circuit to terminals for external connection. The electrically conductive connection consists of a very thin gold wire and a metal layer which are situated on the electrical component or on the integrated circuit. The gold wire is connected to the metal layer by means of thermocompression.
The active parts of an electrical component, particularly of a surface wave filter, or of an integrated circuit (usually also referred to as a "chip"), are now electrically connected to the terminals of the exterior connections or to the housing with very fine gold wires (diameter, for example, 25 .mu.m) by means of thermocompression. This technique represents a generally known and applied technology. The parameters of importance for thermocompression are temperature, pressure and time span of operation. The temperature to which the chip and the terminals are thereby heated generally lies at approximately 350.degree.-400.degree. C. In addition to metallurgical reasons, a high temperature is also necessary for a correspondingly high coefficient of friction between the two metals to be connected, namely, the metal layer designed as a contact spot on the chip or on the component or, respectively, on another contact spot and the gold wire to be connected to the metal layer. Accordingly, the high friction occurs when the wire end which has been melted into a tiny droplet is pressed to the respective contact spot so that a "nailhead" is formed.
In thermocompression, thus it is a matter in a certain sense, of a welding operation which becomes a problem when it is applied given assembly techniques in which a housing of synthetic, for example, of thermoplastic synthetic is employed and/or in which the component or, respectively, the chip is secured by means of adhesive.
Such a method of fastening particularly occurs given surface wave filters which exhibit a substrate of piezoelectric material, for example, mono-crystalline, piezoelectric lithium niobate, in the form of a very thin disk. The filters have an input transducer consisting of a fanned-out metal surface, metal strips on the surface region conditioning the transit time, and at least one output transducer designed in accord with the input transducer on said substrate for generating the surface wave. Surface wave filters of this type, for example, are described in the periodical "Proceedings of the IEEE", April 1971, pages 713/714, incorporated herein by reference. The individual fingers of the input and output transducers are brought together via corresponding lines to contact spots designed as metal layers. These contact spots must be connected to the terminals of external power supplies, which ensues by means of thermocompression, as described above.
The employment of thermocompression for connecting at least two small-surface electrodes disposed next to one another at a small distance on a semiconductor crystal of a semiconductor component to terminal wires by means of cold welding or thermocompression is described, for example, in German No. AS 12 57 976, incorporated herein by reference. Contact spots which are to be electrically connected to one another by means of a fine wire are also present in such semiconductor components or even given integrated circuits upon employment of semiconductor material.
Because of the temperature sensitivity of the housing material and/or of the adhesive, heating to the normally high thermocompression temperature is not possible.
Previously, the method was employed wherein the heat required for the thermocompression was transported to the contacting location via the heated contacting capillary and the gold wire or, respectively, the gold ball. The friction necessary for the welding is generated by means of mechanically or, respectively, electromechanically induced transverse oscillations of the contacting capillary.